Method and apparatus of providing overlay

1. An apparatus comprising an overlay mark, the overlay mark including: a first portion that includes a plurality of first features, each of the first features having a first dimension measured in a first direction and a second dimension measured in a second direction that is approximately perpendicular to the first direction, the second dimension being greater than the first dimension; and a second portion that includes a plurality of second features, each of the second features having a third dimension measured in the first direction and a fourth dimension measured in the second direction, the fourth dimension being less than the third dimension; wherein at least one of the second features is partially surrounded by the plurality of first features in both the first and second directions, and wherein the first features are disposed in a first plane, and the second features are disposed in a second plane different from the first plane.

2. The apparatus of claim 1 , wherein the apparatus further includes a semiconductor device having a first layer as the first plane and a second layer different from the first layer as the second plane.

3. The apparatus of claim 1 , wherein the apparatus further includes first and second photomasks, wherein the first and second portions are respectively disposed within the first and second photomasks.

4. The apparatus of claim 3 , wherein: the plurality of first features have a first pitch measured in the first direction; the plurality of second features have a second pitch measured in the second direction; the first photomask includes a third feature having a first size measured in the first direction; the second photomask includes a fourth feature having a second size measured in the second direction; the first pitch is correlated with the first size; and the second pitch is correlated with the second size.

5. The apparatus of claim 4 , wherein the first pitch is approximately equal to twice the first size, and the second pitch is approximately equal to twice the second size.

6. The apparatus of claim 1 , wherein the plurality of first features have a first pitch measured in the first direction, and the plurality of second features have a second pitch measured in the second direction, wherein the first and second pitches are each correlated with a critical dimension of a semiconductor fabrication technology, the critical dimension being measured in one of the first and second directions.

7. The apparatus of claim 6 , wherein the first and second pitches are each equal to approximately twice the critical dimension.

8. The apparatus of claim 1 , wherein the at least one of the second features is completely surrounded by the plurality of first features in both the first and second directions.

9. The apparatus of claim 1 , wherein: a first subset of the first features have longer second dimensions than a second subset of the first features; and a first subset of the second features have longer third dimensions than a second subset of the second features.

10. An apparatus comprising: a first overlay mark having a group of elongated first gratings that each extend along a first axis, wherein the first gratings each have a first width that is approximately equal to a first distance separating adjacent first gratings, and wherein at least some of the first gratings are longer than other first gratings; and a second overlay mark having a group of elongated second gratings that each extend along a second axis that is approximately perpendicular to the first axis, wherein the second gratings each have a second width that is approximately equal to a second distance separating adjacent second gratings, and wherein at least some of the second gratings are longer than other second gratings; wherein the second overlay mark is partially encircled by the first overlay mark along both the first and second axes; and wherein the first gratings are formed in a first layer, and the second gratings are formed in a second layer different from the first layer.

11. The apparatus of claim 10 , wherein the apparatus further includes a semiconductor device having the first layer in a first plane and the second layer in a second plane.

12. The apparatus of claim 10 , wherein the apparatus further includes a first photomask and a second photomask, wherein the first overlay mark is located on the first photomask, and the second overlay mark is located on the second photomask.

13. The apparatus of claim 10 , wherein: the apparatus further includes a semiconductor device having a critical dimension measured along one of the first and second axes; and the critical dimension is a function of one of the first width, the second width, the first distance, and the second distance.

14. A method of fabricating a semiconductor device, comprising: providing a substrate that contains a first layer and a second layer different from the first layer; forming a first portion of an overlay mark in the first layer of the substrate, the first portion including a plurality of first features, each of the first features having a first dimension measured in a first direction and a second dimension measured in a second direction that is approximately perpendicular to the first direction, the second dimension being greater than the first dimension; and forming a second portion of the overlay mark in the second layer of the substrate, the second portion including a plurality of second features, each of the second features having a third dimension measured in the first direction and a fourth dimension measured in the second direction, the fourth dimension being less than the third dimension; wherein the forming the first and second portions are carried out in a manner so that at least one of the second features is partially surrounded by the plurality of first features in both the first and second directions.

15. The method of claim 14 , further including forming a semiconductor device in the substrate, the semiconductor device having a critical dimension measured in one of the first and second directions; and wherein: the forming the first portion is carried out so that the first group of features have a first pitch measured in the first direction; the forming the second portion is carried out so that the second group of features have a second pitch measured in the second direction; and the critical dimension is a function of one of the first and second pitches.

16. The method of claim 14 , wherein: the providing the substrate is carried out so that the substrate includes a first photomask and a second photomask; the forming the first portion is carried out so that the first portion is formed in the first photomask; and the forming the second portion is carried out so that the second portion is formed in the second photomask.

17. The method of claim 14 , wherein: the forming the first portion includes performing a first dipole photolithography process that uses a first aperture, the first aperture having first openings that are approximately aligned in the first direction; and the forming the second portion includes performing a second dipole photolithography process that uses a second aperture, the second aperture having second openings that are approximately aligned in the second direction.

18. The method of claim 14 , wherein a first subset of the first features have longer second dimensions than a second subset of the first features; and a first subset of the second features have longer third dimensions than a second subset of the second features.